1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
|
# -*- text -*-
# Hey, Emacs! This is a TEXT file.
----------------------------------
README for the caching http_client
----------------------------------
This is the README file for the simple caching http_client.
------------
1. Compiling
------------
1a. Compiling on UNIX.
On UNIX, with a properly configured ACE distribution, just
type make (using GNU make, of course).
1b. Compiling on NT.
Thus far, this code has only been tested under UNIX. A
Windows NT version will be out soon.
------------
2. Executing
------------
2a. Command line parameters.
The program does not support any command line parameters.
2b. General information.
When the program runs, the client offers a ``*'' as a prompt.
At the prompt, you may enter a URL. The client will check to see if
the filename portion of the URL has already been cached. If so, a
message appears saying so. If not, the client will fetch the file
from the HTTP server and then cache it.
Furthermore, the client supports the ``!'' shell escape
command. The content after the ``!'' will be executed by a shell.
To exit the session, send the end-of-file character
(typically, ^D in UNIX).
unix$ ./http_client
* http://www.cs.wustl.edu/cs/Art/brookings.gif
[1] sending request --
GET /cs/Art/brookings.gif HTTP/1.0
Accept: HTTP/1.0
``brookings.gif'' is now cached.
* http://www.cs.wustl.edu/cs/Art/brookings.gif
``brookings.gif'' is already cached.
* !ls
Makefile http_client http_handler.cpp zJAWSAAAa000Yg
brookings.gif http_client.cpp http_handler.h
* ^D
Bye!
unix$ ls
Makefile http_client http_handler.cpp
brookings.gif http_client.cpp http_handler.h
unix$
--------------
3. Limitations
--------------
The caching mechanism as currently implemented requires a
``Content-length:'' to appear in the response header of the HTTP
response. This is because the caching utilizes mmap () to allocate
space for the file to be cached before the file is received. Unitl
the caching mecahnism is extended, you are limited to using servers
which will report the size of the file being transmitted.
Currently, the cache creates temporary files (see the above
sample execution).
The cache is not persistent between executions.
Suggestions and other correspondence should be sent to me:
James Hu <jxh@cs.wustl.edu>
|
